Renault trafic problem

Hi all.i have a problem with my Renault trafic ll29 dci 100 .what the problem is my van has warning lights on.preheating warning light.this came on the other day and my van wouldn't rev up over 2500rpm and was producing a lot of pale smoke.i had to drive the van back home with very little power.once home I turn engine off.afew hour s later I went back out to the van and the warning lights were out and the van drove normal.the problem has come back today and the warning lights are remaining on and lots of pale smoke from exhaust.any help would be grateful.thanks.

Renault trafic problem